public class ReplaceCheck
{
   /**
      A method to replace letters as follows:
      the letter e becomes 3, the letter i becomes 1,
      the letter l becomes 7, and the letter o becomes 0.
      @param str a string
      @return the string with the characters replaced
   */
   public static String replace(String str)
   {
      int l = str.length();
      String s = "";
      for(int i =0;i<l;i++){
         if(str.charAt(i)=='e')
         s+='3';
         else if(str.charAt(i)=='i')
         s+='1';
         else if(str.charAt(i)=='l')
         s+='7';
         else if(str.charAt(i)=='o')
         s+='0';
         else 
         s+=str.charAt(i);
      }
      return s;
   }
}